TFS 01-Crotalaria is Effective Against Nematode Damage of Chili in South-East Asia

Technology fact sheet

31 Oct 2014

Key Facts

  • Uses natural properties of crotalaria to control nematode infestation in chili production.
  • Reduces reliance on and use of synthetic pesticides.

This graph summarizes the results of a sustainability assessment conducted for this technology. The closer the line is to the outer edge of the diagram, the better the technology performs in terms of the particular criterion


  • Nematodes (Phylum nematoda), called roundworms, are the most abundant and geneticallydiverse multicellular organisms. Most are beneficial members of their ecosystems.
  • A few nematode species are parasites of humans, livestock or agricultural crops. Root-knot, cyst and lesion nematodes are pests of a wide variety of crops and are annually responsible for billions of dollars of crop losses.
  • Crotalaria (a genus of herbaceous plants and woody shrubs in the family Fabaceae commonly known as rattlepods) works as a trap crop to reduce the nematode population in soils.
  • The planting and incorporating of crotalaria biomass in the soil before chili production can control nematode damage in tropical areas as proven in north-east Thailand.
Figure 1: Crotalaria (Crotalaria juncea) in the filed[1]      Figure 2: Crotalaria (C. juncea) flower[2]

 History of the technology

  • In north-east Thailand, farmers suffer considerable reduction of yield in chili crops (Capsicum spp.) due to damage by nematodes (Meloidogyne incognita), forcing them to plant other crops or stop growing chili.
  • Crotalaria has been proven to be effective in controlling nematodes in temperate areas, but there was not enough evidence to show its effectiveness in tropical areas.
  • The Japan International Research Center for Agricultural Sciences (JIRCAS) evaluated the effectiveness of crotalaria to formulate practical measures to mitigate damage from nematodes in tropical areas[1]


Where it works

  • The technology can work well in chili production areas in tropical regions with a problem of nematode damage such as north-east Thailand.
  • Successful adopters were chili farmers in north-east Thailand who joined a seminar organized by the Government of Thailand and had access to crotalaria seeds. Non-adopters did not join the seminar and did not have access to the seeds.
  • In Thailand, adopters learned about the technology from the Department of Agriculture, Ministry of Agriculture and Cooperatives.


Technological aspects

  • Crotalaria is sown after soil preparation and at least two months before chili transplanting, at a density of at least 31 kg/ha, depending on site conditions. It is important to sow sufficient seeds to ensure optimal soil coverage by crotalaria.
  • At the end of the flowering stage, usually 50 to 60 days after seeding, the crop is incorporated into the soil mechanically or manually. The field is left to rest for two weeks to allow further decomposition of crotalaria in the soil.
  • After the two weeks, one-month-old chili seedlings can be planted and cultivated as usual.
  • The time frame of a production cycle is six months.
  • In north-east Thailand, one production cycle (crotalaria - chili crop rotation) can be operated in one year; the land remains fallow during the dry season.
  • It is necessary to seed crotalaria in a relatively high density and grow it until the flowering stage to secure sufficient biomass.
Figure 3: Chili root system infected by the southern root knot nematode[3] Figure 4: Root system of infected (left) and healthy (right) plant[4]


Economic aspects

  • In a recent study2, adopters had a net income of THB214,437.50 ($7,265.14). Non-adopters’ net income was THB117,878.13 ($3,993.71).


Table 1. Comparison of costs and yields for adopters and non-adopters


  • Since farmers cannot plant marketable crops during crotalaria production, some income opportunities will be lost. However, the loss is more than offset by the increase in that season's chili harvest and sales.


Environmental aspects

  • Improvement of soil fertility through nitrogen fixation by crotalaria and through nutrients from the decomposition of crotalaria residues.
  • The technology does not use water resources, except during the dry season when irrigation is necessary. No wastewater is produced.
  • Reduced pesticide use.
  • The technology does not use any energy.
  • Before the first cultivation, crotalaria seeds have to be procured externally. Farmers can then multiply and keep their own seeds for the following seasons.


Social aspects

  • One production cycle involves one household member and five paid workers from outside.
  • Farmers using this technology have a higher labour requirement than farmers who cultivate chili using chemical pesticides.
  • The technology is suitable for women: in Thailand, the share of women adopting the technology is 50 per cent.
  • The technology can be operated on any size of agricultural land.


Issues for replication

  • Mixed cropping of chili with Crotalaria sp. did not control nematode infestation sufficiently and is, therefore, not recommended.
  • Although Crotalaria juncea is generally used as a green manure crop in Thailand, it is sometimes hard to obtain its seeds because of insect damage in the flowering stage.
  • Because crotalaria has high efficiency as a green manure, it is expected to reduce the use of chemical fertilizer and mitigate nematode infection.
  • In Japan, crotalaria was shown to be more effective under field conditions than in the laboratory.


Related topics

  • Pepper grafting
  • Tomato grafting



Kushida et al (2003). Effects of Crotalaria juncea and C. spectabilis on hatching and population density of the soybean cyst nematode, Heterodera glycines (Tylenchida: Heteroderidae). Applied Entomology and Zoology. 38 (3):393-399.  Available from

2  Phompanjai, P. et al (2012). Control of root gall disease in chilis caused by root-knot nematodes. In: High value vegetables in southeast Asia: production, supply and demand. Proceedings, Seaveg 2012.104-108, p.107f.


Source of photographs



  • S. Miyata, N. Tangchitsomkid. Email:
  • Atsuhiko Kushida, Laboratory of Plant Nematology, National Agricultural Research Center for Hokkaido Region. Email:



Leave Your Comments

Log in or register to post comments